Low melting point glass for covering electrodes, and glass ceramic composition for covering electrodes

Abstract

A low melting point glass for covering electrodes, consisting, as represented by mass percentage based on the following oxides, essentially of:

What is claimed is:  
     
       1. A low melting point glass for covering electrodes, consisting, as represented by mass percentage based on the following oxides, essentially of: 
       
         
           
                 
                 
               
                     
                     
                 
                     
                   Mass percentage 
                 
                     
                     
                 
                     
                 
                 
                 
                 
               
                     
                   PbO 
                   20 to 60%, 
                 
                     
                   Bi 2 O 3   
                    0 to 30%, 
                 
                     
                   B 2 O 3   
                   20 to 55%, 
                 
                     
                   SiO 2   
                    0 to 10%, 
                 
                     
                   Al 2 O 3   
                    0 to 15%, 
                 
                     
                   MgO + CaO 
                    0 to 35%, 
                 
                     
                   SrO 
                    0 to 35%, 
                 
                     
                   BaO 
                    0 to 35%, 
                 
                     
                   ZnO 
                    0 to 8%, 
                 
                     
                     
                 
             
                
                
                
               
               
                
               
            
             
                
                
                
                
                
                
                
                
                
                
               
            
           
         
       
       wherein PbO/B 2 O 3  is not higher than 57/32 and the low melting point glass has a softening point of from 520 to 650° C. 
     
     
       2. The low melting point glass for covering electrodes according to  claim 1 , which further contains SnO 2  and/or CeO 2  in a total content of at most 4.8% by mass percentage. 
     
     
       3. The low melting point glass for covering electrodes according to  claim 1 , which has an average linear expansion coefficient in a range of from 50 to 350° C. of from 60×10 −7  to 90×10 −7 /° C. 
     
     
       4. The low melting point glass for covering electrodes according to  claim 1 , which has a dielectric constant of at most 10.5. 
     
     
       5. A glass ceramic composition for covering electrodes, comprising a powder of the low melting point glass for covering electrodes as defined in  claim 1  and a powder of an inorganic pigment, wherein the powder of an inorganic pigment is contained in a proportion of from 0.5 to 40 parts by mass per 100 parts by mass of the powder of the low melting point glass for covering electrodes. 
     
     
       6. The glass ceramic composition for covering electrodes according to  claim 5 , wherein the inorganic pigment is at least one member selected from the group consisting of TiO 2 , Al 2 O 3  and ZrO 2 . 
     
     
       7. The glass ceramic composition for covering electrodes according to  claim 5 , which has an average linear expansion coefficient in a range of from 50 to 350° C. of from 60×10 −7  to 90×10 −7 /° C. 
     
     
       8. A plasma display device having a front substrate, wherein transparent electrodes formed on a glass substrate constituting the front substrate are covered by the low melting point glass for covering electrodes as defined in  claim 1 . 
     
     
       9. The plasma display device according to  claim 8 , wherein the front substrate has a transmittance of light with a wavelength of 550 nm of at least 70% and a turbidity of at most 30%. 
     
     
       10. A plasma display device having a rear substrate, wherein electrodes formed on a glass substrate constituting the rear substrate are covered with a fired product of the glass ceramic composition for covering electrodes as defined in  claim 5 . 
     
     
       11. The low melting point glass for covering electrodes according to  claim 1 , wherein the ratio of the content of SiO 2  to the total content of SiO 2  and B 2 O 3  is at most 0.2.